Many photopolymerization reactions utilizing an organic dye as a light sensitizer (initiator) and polymer image recording processes based on the photopolymerization reaction are well known, but the sensitivity thereof is usually as low as ISO 10.sup.-3 or less, which is very inferior to that of silver halide photographic materials. Although the polymer images obtained by photopolymerization have various useful properties in utilization, which are not provided by silver halide photographic materials, use thereof is restricted due to such limited sensitivity.
Further, in the case of forming visible images, particularly for use as hard copies, the use of the photopolymerization image recording materials is very restricted because of having such low sensitivity, in spite of having the great advantage of not using silver, which is an expensive and rare resource. Accordingly, if the polymer imaging material can be formed to have a high sensitivity equal to that of silver halide, it would become possible not only to greatly expand the extent of utilization of the field of image formation based on photopolymerization, for example, for printing plates, photoresists, etc.; but also to greatly expand the use thereof as inexpensive hard copy materials.
Hitherto, as high sensitivity processes for forming a polymer image, various attempts wherein polymerization is carried out using silver halide as a light sensor by utilizing a high amplification rate of it in a development stage have been done.
For example, there are: (1) a process wherein a polymerization reaction is caused by a radical formed in the reducing agent oxidized in the development step of silver halide, as described in Japanese Patent Applications (OPI) Nos. 78153/83, 169143/83, and 174947/83 (the term "OPI" as used herein referring to a "published unexamined Japanese patent application"); (2) a process wherein a polymerization reaction is caused by a radical formed from perioxide by a redox reaction between the silver image obtained by development of silver halide and the peroxide, as described in Japanese Patent Publication No. 18862/66, corresponding to U.S. Pat. No. 3,241,962 (3) a process wherein a polymerization reaction is caused by a radical formed from peroxide by a redox reaction between silver ion which remains in the unexposed area and dissolved therefrom after development of silver halide and the peroxide as described in Japanese Patent Publication No. 2657/64, corresponding to U.S. Pat. No. 3,345,164; (4) a process wherein a polymerization reaction is caused by a radical formed from peroxide by a redox reaction between iron (I) salt remaining in the unexposed area and the peroxide after development of silver halide with the iron (I) salt, as described in U.S. Pat. No. 3,029,145; and (5) a process wherein a polymerization reaction is directly caused by the reducing agent remaining in the unexposed area after silver halide is developed, as described in Japanese Patent Application (OPI) No. 149939/80, corresponding to U.S. Pat. No. 4,287,290.
These processes are those wherein a radical is formed directly or by a subsequent reaction, using any of raw materials taking part in the development step of silver halide (silver halide, reducing agent) and products (silver image, oxidation product of reducing agent). In these causes, it is supposed that the polymer image is formed in a sensitivity near that of silver halide. However, all of them require wet processings for carrying out development of silver halide and the step of polymerizing by radical formation, and the processes using peroxide have a fault of causing great deterioration of the recording material, or the occurrence of fog due to polymerization in the dark by radicals formed by decomposition of the peroxide. Further, they generally have a fault in that the polymerization reaction requires a long time.